GDS provides the URLs for access to the data it
publishes. Here we give an overview about how to create, read and write
a variable and its attribute values. Let’s use the name “~/TRY/TEXT” as
a sample variable. The name denotes a variable named “TEXT” located in
the subdirectory “TRY” in the user's home directory “~”. (The “aval”
attribute of the variable is only needed to keep the demo simple – if
you would like more detailed information, please check our
documentation).

As you begin with a URL (indicated below), you will be prompted by a
login dialogue box before any operation can be performed. Please
type in “guest” as your user ID, and “guest” as your password. The
operations will be performed on your own home directory. You may notice
that other users exist, but since you do not have any access rights,
you of course won’t be able to view any of their data.

Now, let’s show you how to create a variable that contains text
content. The data stored in the variable can be used from any location,
just by accessing the correct URL (see below).

This creates the variable and indicates that the
variable type is a “text” value. Remember, other users have also
performed this demonstration, so you will probably see that this
variable already exists. You can inspect the data published in the
“guest” account by using the ADI Browser.

Reading an Attribute of an ADI Variable

To access the attribute aval (actual value) of the variable named ~/TRY/TEXT in the user's home directory, use the URL:

The browser will show the raw data content of the variable. Other data
types, e.g. images, will be transferred to the client in a properly
mime-encoded format, so the data can be displayed correctly by the user
agent.

Since we have created the text-type variable, the
aval-attribute will contain the current value. The attribute sval (scheduled
value) is the write entry for the attribute aval (actual value). GDS
will ensure the content of sval is copied into aval.
The results of the modification can be observed via the GDS browser or by using a URL to read aval of the variable.